System of distribution for oscillatory electrical currents.



L. COHEN. SYSTEM OF DISTRIBUTION FOR OSGILLATORY ELECTRICAL OURRENTS.

' APPLICATION FILED 13120.14, 1912.

1,123,098, Patented Dec.29,1914,

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To all whom it may concern:

Be it known that L-Loms COHEN, a citizen of the United States, residing at Cambridge, in. the county of Sufl'olk and State of Massachusetts, have invented certain new and useful Improvements in Systems of Distribution for Oscillatory Electrical Currents, of which the following is a specification. 4 This invention relates to a system of distribution for oscillatory or alternating electrical currents, and has particularly in view a means for distributing currents of that character from one circuit to another in such a manner asto provide a system of great flexibility, while at the same time se curing an extremely stiff working cir-.

cuit possessing great utility in its application to wireless signaling. While the invention is of special utillty in its application tov Wireless signaling, it is useful in any work where high-frequency alternating currents are employed and it is desirable to provide and maintain conditions which cause the working circuit to be delicately sensitive and responsive only'to currents of a definite frequency transmitted thereto from the supply circuit. Accordingly, the distinctive features of the invention may best be explained by brief reference to the general conditions prevailing in wireless telegraph systems as ordinarily practiced. .In this connection, however, it

is only necessary to compare the present invention with the ordinary and usual means employed in wireless telegraph systems for maintaining electrical communication between the two oscillating-circuits. It is well known that in the useof high frequency oscillatory currents, damped orjundamped, for wireless signaling either in transmit: ting or receiving signals, two oscillating circuits are employed to secure operative conditions, and these two circuitsare maintained in electrical communication, electromagnetically, ,by means of a'transformer, and it is the primary ob ect of thepresent I invention to entirely eliminate the use of a transformer for that purpose between two oscillating circuits, and to substitute therefor'another form of coupling which not only accomplishes all of the electrical functions of the transformer in a different manner,-but atthe sametime secures improved results in the general flexibility of the systern andthrough the stifieningo f the worky Specification of Letters latent.

Patented n t; as, rent.

Application filed December 14,1912. Serial No. 736,875.

ing circuit that is not possible of attainment through the use of an electromagnetic coumunication between two circuits of the;

character referred to can best be understood by reference to the accompanying drawings, in wh1ch F igures, 1 and 2 are diagrams schemati cally showing the general arrangement of two oscillating circuits coupled together electrost'atically, 1 as contemplated by the present invention. Fig. 3 is a diagrammatic illustration of the invention in its application to the receiving set of a wireless telegraph system. Fig. 4 is a diagrammatic vlew illustrating a combination of electrostatic and electromagnetic couplings for the receiving set of a wireless telegraph system.

Fig. 5 is a diagram illustrating an application of the invention to the sending set of a wireless telegraph system.

Referring specifically to the embodiments of the invention illustrated and suggested in the drawings, it-will be observed that in Fig. 1 of the drawings, the numeral 1 deslgnates a source ,of oscillatory electrometive force, such for instance as an alternator, an arc, or an induction coil, the same i being included in what may be termed the supply or generating circuit a, while the working clrcuit to be operated may be generally indicated by the reference letter 1). 1n the said illustration of Fig. 1 of the drawings, the circuit a includes a resistance 2, an inductance 3,and a vari-' able tuning condenser 4, while the other.

circuit 6 likewise includes a resistance 5, an inductance 6, a variable tuning condenser 7, and the electrical instrument device or apparatus, designated by 8 which is intended to be operated by the electrical impulses or currents transmitted to the circuit 1) from the circuit a. These two circuits are electrostatically coupled by means of a variable condenser 9 of relatively small capacit said coupling necessarily including suitab e stants of the two circuits so that the sum of.

the capacities 9 and 7, multiplied by the inductance 6 is equal numerically to the product of inductance 3 and capacity 4, and if he source of I). M. l. (1) produces a forced oscillation of a definite frequency, then both systems must be adjusted to be in resonance for that particular frequency. The condenser 9, which is the coupling condenser, must be made relatively small, about 1/50 to 1/10 of the capacity 7, in which case we get a current flow in circuits at and b. If the inductance 6 or the capacity 7 is changed somewhat, the current in the circuit 1) will be reduced, whilethe current in the circuit a is not affected; in other words, the said two circuits are independent in the same sense as the two circuitsof an electromagnetically coupled systemfand it will also be understood that the value of the coupling capacity-'Qto be used dependslargely onthe frequency" and also to some-extent on the other electrical constants, which however is a factor that can readily'be determined, and has been determined, mathematically.

The arrangement, schematically shown in Fig. 2. is exactly the same as that of Fig. 1.

of the drawings, excepting that in Fig; 2 the condenser 4 and.the inductance and resistance 3' and 2 are interchanged, and it will, therefore be obvious that the arrange. ment of circuits shown in Fig. 2 will operate in exactly the same way as the arrangement of circuits shown in Fig. 1. However, it may be noted at this point that the current in the elements 6, 5 and 7 of circuit 6 will be approximately opposite in phase,

' that is the current passing through the coupling condenser 9 will be approximately the i spectively.

difference of the currents in 6, 5, and 7 re- Consequently, while a very small current passes through the small coupling condenser 9 we may have fairly large currents in the circuit b.

In Fig. 3 of the drawings, the new electrostatic coupling is shown-in its application to the receiving set of a wireless telegraph system. In this diagram, the letter a may still designate generally what has been termed the supply or generating circuit,.and the letter Z) the working circuit including the various branches and elements of the latter. In said illustration of Fig. 3,10 designates the antenna, 11 a loading inductance coil, and 12 the ground, thus completing the sup. ply circuit. Included in the general working circuit 6 is the inductance 13, a variable tuning condenser 14, a large condenser 15 generally called a stopping condenser, the etector 16, and the receiving telephone 17, thesaid stopping condenser having the funca which is transmitted through the electro static coupling 9, 0, a, to the oscillating circuit b, 13, 14, and sets it in oscillation electrically. The energy of this oscillating circuit is gradually absorbed by the detector 16 which causes the signals to be indicated in the telephone.

As herein indicated, Fig. 4 of the drawings shows an arrangement adapting the invention to the receiving set of a wireless telegraph system wherein the electrostatic coupling feature is combined with an electromagnetic or transformer coupling. In this illustration, circuits and elements corresponding to circuits and elements in Fig. 3 are correspondingly numbered, in each case the electrostatic coupling consisting of the small condenser 9 and the leads 0 and (1. However, in the combination'shown in Fig. 4. the tuned circuit designated bv e and including a tuning condenser 18 is coupled 'electrostatically to the cludes a tuning condenser 19 is coupled electromagnetically to the tuned circuit 6 through the transformer 20. In this arrangement, shown in Fig. 4, that portion of the circuit which may still be referred to y v as the main. working circuit 6 includes the stopping condenser 15. the detector.16, and

the telephone 17. The said arrangement shown in Fig. 4 of the drawings gives remarkably sharp tuning and is therefore very effective in the elimination of all disturbancescgenerallv caused by other signals of different frequencies;

In Fig. 5 of the drawings is suggested an application of the invention to the sending set of a wireless telegraph system. In this arrangement, what may still be characteri zed generally as the supply or generating circuit, is designated by the letter a while in this instance the Working circuit 6 is-the antenna circuit consisting of the antennae 10 the coil 11 and the groundc'onnection 12. These two circuits are electrostatically coupled by the same/electrostatic coupling already described, namelyby the variable 5 condenser 9 of small capacity and the leads 0 and d. Referring further .to the details of the circuit shown in Fig. 5, 21 designates the leads from a high potential source, 22

the spark gap, 23 a variable.condenser,.and

24 an inductance. With this arrangement 'of circuits in the sending set of a wireless system, when the condenser 23 is chargeduto the critical point or to its maximum poteniso tial, depending on the length of the gap 22, a spark occurs in the said gap, thereby shortcircuiting tli-e circuit- :22," 23 and 2a, whereupon the condenser 23 discharges itself through the inductance 24, when the resistance of the circuit is small as is usually the case, oscillations are set up in the circuit. If the constants of the antenna circuit and of the oscillating circuit 22, 23, and 24 are arranged so as to he in resonance and the 1 capacity of the coupling condenser 9 is properlyadjusted, the energy of the oscillating circuit, 22, 23, 24 will be gradually transmitted to the antenna circuit which .will set it in oscillation and the energy gradually radiated in the form of electromagnetic waves. performed by the condenser 9, in the transmitting or sending set, are electrically the same as in the receiving set of a wireless telegraph system, in each instance being a very superior substitute in many respectsto the ordinary form of electromagnetic coupling through the employment of the transformer.

Referring further to the functions of the small coupling condenser between the two oscillating circuits, the following explanation is made:'With a given E. M. F. 1m-

pressed on one circuit, a variation in the 30 capacity in the coupling condenser 9 will cause a variation in the intensity of the current in the other circuit (the working circuit b though the resonance condition of the circuit 6 is maintained. The changing of the capacity of the coupling condenser 9 also changes the stiifness of the system or circuit 6, the smaller the capacity of the said coupling condenser the greater the stiffness electrically that is given the system or circuit 6, that is to say, it will be less and less responsive to potentials of frequencies differing from its own electrical periodicity. In practical work dealing with oscillatory currents, the capacity of the coupling condenser 9 is so adjusted as to give the desired stifiness, and yet admits the transmission of sufilcient current from one circuit to the other. Sometimes a compromise has to be affected, that is to say the intensity of the current to be transmitted may be somewhat sacrificed so as" to obtain an extremely stifi electric circuit.

From the foregoing, it is thought that the essential features of the invention will In these operations, the functionsdescription, but it is also to be understood 7 that I do not limit my invention to the specific circuits and applications shown in the drawings, as the same is susceptible of general application as a coupling between separate oscillating circuits employed for any purpose, and various changes'in the arrangement of parts and in theuse of details may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

I claim:

1. A system of receiving wireless signals including a tuned antenna circuit, a second tuned circuit, and an independent condenser of relatively small capacity to the tunlng capacities of the said two tuned circuits and arranged to constitute the coupling or link between said two circuits to transmit electrical energy from one to the other.

2. A system of distributing oscillating electrical currents including two separate tuned circuits, and an electrostatic coupling connected by leads with said separatecircuits, and consisting solely of a condenser of relatively small capacity.

3. The method of transmitting messages by Hertzian waves which consists in generating electric currents in a closed oscillatory circuit, transmitting the alternating difference of potential between two points in said circuit toan open oscillatory circuit having its electrical constants tuned harmonically with said closed circuit, through the medium of an electrostatic coupling circuit and adjusting the capacity of said electrostatic coupling until the wave length in said coupling clrcuit is so short and weak as to be practically of negligible efi'ect.

4. Apparatus for wireless telegraphy comprising a closed and an open circuit properly tuned to each other, and electrostatic couplings between a pair of points 111 the one circuit, and a pair of points in the other, each to each. said points in each circuit being electrically distant.

In testimony whereof I hereunto afiix my signature in the presence of two witnesses.

LOUIS COHEN. "Witnesses i EMORY L. GRorF, JAMES H. MARR. 

